The present invention relates to a pump for dispensing a liquid product from a container. More particularly, it relates to an inexpensive, molded plastic, reciprocating piston pump for this purpose which is leak-resistant.
Heretofore, many dispensing pumps have incorporated pressure-actuated check valves in their outlet passages. However, ball check valves are prone to leak if the pump is tipped or turned over, and all pressure-actuated check valves are prone to leak if enough pressure develops within the container. This might occur if the pump is mounted on a flexible-walled container and the container is squeezed or if the dispenser is stored in a hot environment.